Electroless copper plating solution and process for formation of copper film

Abstract

Disclosed are an electroless copper plating solution comprising a copper ion, a copper ion-complexing agent, a reducing agent and a pH-adjusting agent, the plating solution comprising a trialkanolmonoamine or a salt thereof as a complexing agent and accelerator in an amount giving a higher copper deposition speed than the copper deposition speed obtained when the trialkanolmonoamine or salt thereof is present in an amount sufficient to complex the copper ion but not enough to function as the accelerator, and 1.2×10 -4 to 1.2×10 -3 mole/l of an iron ion compound as a reaction initiator and/or 1.92×10 -4 to 1.92×10 -3 mole/l of at least one compound selected from the group consisting of pyridazine, methylpiperidine, 1,2-di-(2-pyridyl)ethylene, 1,2-di-(pyridyl)ethylene, 2,2'-dipyridylamine, 2,2'-bipyridyl, 2,2'-bipyrimidine, 6,6'-dimethyl-2,2'-dipyridyl, di-2-pyridylketone, N,N,N',N'-tetraethylethylenediamine, napththalene, 1,8-naphthyridine, 1,6-naphthyridine, tetrathiafurvalene, α,α,α-terpyridine, phthalic acid, isophthalic acid and 2,2'-dibenzoic acid as an agent for improving the physical properties of a plating film, and a process for forming an electroless copper deposition film by using this electroless copper plating solution.

We claim: 
     
       1. A process for formation of a copper plating film, which comprises immersing a material to be plated, which is susceptible to deposition of copper, in an electroless copper plating solution comprising copper ions, a reducing agent, a pH-adjusting agent, a trialkanolmonoamine or a salt thereof in an amount sufficient to act as a complexing agent and accelerator, an iron ion compound selected from the group consisting of at least one of ferrous halide salts, ferric halide salts, ferrocyanide compounds and ferric cyanide compounds as a reaction initiator, and at least one compound selected from the group consisting of pyridazine methylpiperidine, 1,2-di-(2-pyridyl)ethylene, 1,2-di-(pyridyl)ethylene, 2,2'-dipyridylamine, 2,2'-bipyridyl, 2,2'-bipyrimidine, 6,6'-dimethyl-2,2'-dipyridyl, di-2-pyridylketone, N,N,N',N'-tetraethylethylenediame, naphthalene, 1,8-naphthyridine, 1,6-naphthyridine, tetrathiafurvalene, α,α,α-terpyridine, phthalic acid, isophthalic acid and 2,2'-dibenzoic acid as an agent for effecting physical properties of said plating film, to thereby deposit said copper on a surface of the material to be plated at a deposition speed higher than the copper deposition speed obtained when the trialkanolamine or salt thereof is present in amount sufficient to complex the copper ion but not enough to function as the accelerator, wherein (i) said iron ion compound is present in an amount of at least 2.4×10 -4  mole/liter (100 mg/liter) and said agent for effecting the physical properties is present in an amount of at least 3.2×10 -4  mole/liter (50 mg/liter); (ii) said iron ion compound is present in an amount of at least 1.2×10 -4  mole/liter (50 mg/liter) and said agent for effecting the physical properties is present in an amount of 6.4×10 -4  mole/liter (100 mg/liter); or (iii) said iron ion compound is present in an amount of 7.2×10 -4  mole/liter (300 mg/liter) and said agent for effecting the physical properties is present in an amount of at least 1.9×10 -4  mole/liter (30 mg/liter). 
     
     
       2. A process according to claim 1, wherein the electroless copper plating solution comprises up to 1.2×10 -3  mole/l of the iron ion compound and up to 1.92×10 -3  mole/l of the agent for effecting the physical properties of the film. 
     
     
       3. A process according to claim 1, wherein the iron ion compound is at least one metal ferrocyanide or metal ferricyanide. 
     
     
       4. A process according to claim 1, wherein the agent for effecting the physical properties of the film is at least one member selected from the group consisting of 1,2-di-(2-pyridyl)ethylene, 2,2'-bipyridine, 2,2'-bipyrimidyl and 1,8-naphthyridine. 
     
     
       5. A process according to claim 1, wherein the trialkanolmonoamine or the salt thereof is contained in an amount of 1.2 to 30 moles per mole of the copper ion in the electroless copper plating solution.